A novel kind of guitar Tone control

[eschertron]

Hey, if you can just upload the images I'll quote your post and display them full-sized.

Thanks!

Steve Ahola

No problem, my friend! I am always eager to learn something new!

[Steve A.]

edit: an exercise in posting pictures. Whew! Even with Steve's step-by-step, it took about 10 minutes and half a dozen tries!

Hey, if you can just upload the images I'll quote your post and display them full-sized.

Thanks!

Steve Ahola

[Steve A.]

I don't think that was Mark
It was a link back to this thread. jbefumo is an actual person if memory serves.
(GFS Mini Humbuckers? | Harmony Central)

I will take your word on that. I guess I misinterpretted the reference to the thread here thinking that it was his thread. My bad!

I also have a 2-tiered capacitor bypass on the volume controls (described here: http://music-electronics-forum.com/t15821/), which keeps things from getting muddy when the volume controls are turned down.

Steve A.

[eschertron]

Can you post a picture of the stack with a SWEEP through all of the settings? I think that would give us a good idea of the effect of the control.

So the higher input impedance loads the signal by a 'few' dB. Nothing major. Play with the two caps to get different curves for emphasis and de-emphasis. I tried this because I wanted something opposite of a standard guitar tone control.

Credit where it's due: This experiment sparked by Merlin's preamp book where he takes the reader through the basics of frequency-dependent 'tone' networks. A basic LF control.

edit: an exercise in posting pictures. Whew! Even with Steve's step-by-step, it took about 10 minutes and half a dozen tries!

[g1]

I don't think that was Mark
It was a link back to this thread. jbefumo is an actual person if memory serves.
(GFS Mini Humbuckers? | Harmony Central)

[Steve A.]

Did you intend to include a link Steve?

At this point I have no idea where exactly I found it but I can assure you that Mark's post was the only memorable one there...

Steve A.

[Tom Phillips]

...I found this thread over at Harmony Central in a post by Mark's pseudonym over there...

Did you intend to include a link Steve?

[Steve A.]

If models can be modified, or additional models programmed, I'd be interested in that also!

Figure the input impedance as whatever you are using (pickup makers may provide actual values) or just guesstimate at 7k or so. Output impedance should be close to 1M if you are feeding an amp directly, and using the 'high' input.

On the James stack, if R1 and R2 are equal, then if RB is centered (using a linear pot) you will drop "about" 6dB
https://www.ampbooks.com/mobile/amp-...tack-analysis/

I don't remember the exact values that I used, but if R1 + R2 + RB add up to about 250k to 500k they should load the pickups the same as a normal tone control. Hope that helps.

edit:
[ATTACH=CONFIG]39563[/ATTACH]
just a quick simulation. I have no idea if the values are what I used, or if they'd sound good. but you can see the ~6dB load. Turn UP the bass and let more signal through, effectively reducing the load at the string's fundamental frequencies.

Can you post a picture of the stack with a SWEEP through all of the settings? I think that would give us a good idea of the effect of the control.

Thanks!

Steve Ahola

P.S. I found this thread over at Harmony Central in a post by Mark's pseudonym over there...

[Richard]

Not from me. I understand electronics like plumbing, not calculus.

[eschertron]

Thanks, I see how you used extreme values to remove the extraneous part of the circuit. Did you use the DCR of the pickup for your source resistance?

Yes.
...and I sense a subtle admonishment that using a dynamic impedance for the pickup (in the 50k range?) will reduce the pristine clarity of the results

[Richard]

Thanks, I see how you used extreme values to remove the extraneous part of the circuit. Did you use the DCR of the pickup for your source resistance?

[eschertron]

Does anyone know to program models into Duncan's TSC?

Escherton, what values did you use? I'm curious as to how you kept the insertion loss to 6dB, When playing around with the TSC I just raise the values of the unused portion but I'd like to be able to edit the models for a more accurate response. How do I know the source and output impedance of my guitar pickups.

If models can be modified, or additional models programmed, I'd be interested in that also!

Figure the input impedance as whatever you are using (pickup makers may provide actual values) or just guesstimate at 7k or so. Output impedance should be close to 1M if you are feeding an amp directly, and using the 'high' input.

On the James stack, if R1 and R2 are equal, then if RB is centered (using a linear pot) you will drop "about" 6dB
https://www.ampbooks.com/mobile/amp-...tack-analysis/

I don't remember the exact values that I used, but if R1 + R2 + RB add up to about 250k to 500k they should load the pickups the same as a normal tone control. Hope that helps.

edit:

just a quick simulation. I have no idea if the values are what I used, or if they'd sound good. but you can see the ~6dB load. Turn UP the bass and let more signal through, effectively reducing the load at the string's fundamental frequencies.

[Richard]

Does anyone know to program models into Duncan's TSC?

Escherton, what values did you use? I'm curious as to how you kept the insertion loss to 6dB, When playing around with the TSC I just raise the values of the unused portion but I'd like to be able to edit the models for a more accurate response. How do I know the source and output impedance of my guitar pickups.

[eschertron]

Can't wait to see what happens as this thread is resurrected and developed. I really enjoy messing with the guitar circuitry.

I did the bass half of a james stack (textbook bass control) on a strat style guitar once, because I didn't like the 'dulling' effect of rolling off all the treble before I got to the frequencies of interest. The insertion loss of the control at flat was -6dB. I felt I could live with that. The effect of the control was a bit subtle, though, especially with clean tones and brighter pickup selections.

[Richard]

I'm definitely going to have to check these ideas out.